While there have been many recent proposals for developing solar heating systems to replace or at least substantially replace or compliment conventional heating systems, these have contemplated complex installations in order to integrate such systems with the conventional heating systems the latter then serving as backup units. Proposals such as contained in the applicant's co-pending application entitled THERMOSIPHON SOLAR SPACE HEATING SYSTEM WITH PHASE CHANGE MATERIALS previously cross-referenced, attempt to utilize solar heating in a form which does not involve the window structure of the house itself but rather is independent thereof, either installed in the walls or along the outer baseboards of the house. Many solar heating proposals can be criticized in that they are not conveniently packaged for conventional buildings and usually require an independently and remotely positioned solar heat storage system making it necessary to transport a heat absorbing gas or liquid to and from the remote storage through piping or ducting. Additionally, prior systems are not particularly architecturally compatible with the existing buildings and building practices; and, they do not lend themselves to a degree of structural simplicity which would enable them to be installed and utilized by the average homeowner. More importantly, the prior art does not appear to be adapted for use in conjunction with windows. There is a need for a solar heating device which the homeowner can acquire locally and install himself when briefly instructed in a manner requiring no interfacing with existing heating systems. In the present invention no attempt is made to handle all of a building space heating load but it is possible to supply a significant fraction of the heat load requirements can be met as will become apparent.
U.S. Pat. Nos. 4,003,367 and 4,055,055 illustrate the application of thermosiphonic principles to the making of a water heater and a boiler based on the collection of solar energy. However, neither of these disclosures are adapted for use as self-contained units and appear limited to the specific application as water heating devices.
U.S. Pat. No. 4,073,284 illustrates the use of a crystalline phase change material in a solar heating device operated by the saturated vapor of a heat carrier which is used to exchange heat with a phase change material having a storage mass capable of absorbing heat energy in the form of latent heat at a temperature just above room temperature. However, the principle of operation relies on the vaporization of a condensate, the pressure of which is regulated by a ducting system which is in communication with a bellows associated with the unit in order to control condensate level. This unit is designed to operate horizontally at ceiling level where heat is not efficiently distributed. In view of the necessity of operating against gravity between a liquid and a condensate phases in the heat collection system, the unit appears inherently unsuitable for window locations.
U.S. Pat. No. 4,062,351 discloses a water collection through panel having inlet and outlet ports connected to a piping system and presumably thence to a storage facility. In one embodiment disclosed in 4,062,351 (FIG. 19) it is stated that a thermosiphoning process can take place if the unit is tilted up and further it states that a supplemental use of heat retaining crystals can surround the heat transfer pipe in a unit employing fins to assist in exchange of heat from the panel to the material flowing in the transport pipe which presumably leads to a larger heat storage facility. The nature of the crystalline material referred to is not disclosed. This unit employs associated piping to take away energy from the panel rather than utilize it in situ and is therefore not self-contained and is not adapted for use as a window unit.
U.S. Pat. No. 4,034,736 discloses the use of a plurality of horizontally disposed slats resembling a venetian blind in a solar collector, however, air is used to be circulated by a fan through the solar collector for removing energy therefrom and for being sent to a bulk storage facility or to the rooms of a house via air ducts. The use of phase change materials for a high density heat storage and direct radiation or convection is not disclosed.
There is therefore a need for a new and improved structure which will fulfil the requirement of providing a partial or fractional contribution to a building's energy requirements based on solar exposure and heat storage in conjunction with a building's windows and which can be subsequently deployed to heat the building.